Kilohertz (kHz) in Aviation Communication

Kilohertz (kHz) in Aviation Communication

Radio Spectrum: The basic building block of radio communications is a radio wave. Radio waves have the longest wavelengths in the electromagnetic spectrum. Like waves on a pond, a radio wave is a series of repeating peaks and valleys. The entire pattern of a wave, before it repeats itself, is called a cycle. The wavelength is the distance a wave takes to complete one cycle. The number of cycles, or times that a wave repeats in a second, is called frequency. Frequency is measured in the unit hertz (Hz), referring to a number of cycles per second. One thousand hertz is referred to as a kilohertz (kHz), 1 million hertz as a megahertz (MHz), and 1 billion hertz as a gigahertz (GHz). The range of the radio spectrum is considered to be 3 kilohertz up to 3,000 gigahertz.

In aviation, kilohertz (kHz) is a standard unit of frequency equal to 1,000 hertz. It plays a crucial role in defining the operating frequencies of aviation communication systems, especially in the VHF (Very High Frequency) and HF (High Frequency) bands.

Use in Aviation

Kilohertz is commonly used to specify communication frequencies for:

• HF communications: Generally used for long-distance and transoceanic flights, where VHF line-of-sight limitations are impractical. These frequencies are typically listed in kilohertz (e.g., 5,598 kHz).
• VHF communications: While frequencies in this band are often expressed in megahertz (MHz), the actual increments and channel spacings (e.g., 25 kHz or 8.33 kHz spacing) are derived from kilohertz-level resolution.

Importance

• Ensures accurate tuning between pilots and air traffic control (ATC) for safe and coordinated communication.
• Plays a key role in navigation systems such as NDBs (Non-Directional Beacons), which transmit in the LF/MF bands measured in kilohertz.
• Standardized frequency assignments help avoid interference and support international aviation operations.

Related Units

• Hertz (Hz): The base unit of frequency.
• Megahertz (MHz): Equal to 1,000 kilohertz, often used for VHF communication listings.

Example Frequencies

• HF ATC Channel: 5,598 kHz (used in oceanic control sectors)
• NDB Navigation: Typically operates between 190 – 535 kHz
• VHF Comm Channels: 118.000 MHz – 136.975 MHz (spacing based on kilohertz resolution)

See Also

• VHF (Very High Frequency)
• HF (High Frequency)
• Radio Communication in Aviation
• NDB (Non-Directional Beacon)